Process of treating artificial thread



Patented 0a. 17, 1933 UNITED STATES PATENT OFFICE' PROCESS OF TRE ATING ARTIFICIAL Du Pont Rayon Company, New York, N. corporation of Delaware Application February 28, 1930 Serial No. 432,263

No Drawing.

9 Claims.

This invention relates to a process of treating artificial thread and particularly to a process of bleaching artificial thread produced by the viscose process.

Recently, there has developed in the trade an urgent and extensive demand for cones composed of bleached artificial silk. According to one of the modes of procedure, the cones are made directly from the bucket cakes. Inasmuch as the bleaching of the cones presents serious difiiculties, it is desirable to bleach the cakes prior to coning. The cakes in almost all treatments performed after removal from the bucket require some sort of inserts. When subjected to the desulphuring operation, the cakes after removal from the bucketsv are usually provided with resilient foraminous aluminum inserts. To eliminate changing of the inserts and avoid excessive handling, it is desirable to subject the cakes and inserts utilized in the previous treatments to the bleaching operation. Aluminum, however, is attacked and corroded by the usual bleaching solutions and there results a contaminated product. Hence, in order to employ aluminum inserts or carriers in the bleaching operation, it becomes necessary to inhibit the corrosion thereof by the bleaching solution.

I have found that I can succesfully bleach -artificial yarn produced from viscose either in the dried or gel (undried) state, even when said yarn is contained on aluminum carriers, such as bobbins, buckets or inserts within the cakes with the usual bleaching solutions, without any subi, stantial corrosion of the carriers by introducing 35 in said bleaching solution an agent inhibiting the corrosive action of the bleaching solution thereof. i

It is therefore an object of this invention to bleach artificial yarn, produced by the viscose process, in the dried or gel state contained on aluminum carriers without any substantial corrosion of said carriers. I j I Another object of thisfinvention is to provide a method of bleaching artificial yarnproduced from viscose and disposed on aluminum carriers by subjecting said yarn and carriers. to a bleaching solution containingan agent which inhibits the corrosion of saidcarriers.

Another object of this invention is to provide a method of bleaching artificial yarn produced from viscose and disposed on aluminum carriers which comprises subjecting said yarn and carriers to the action of a bleaching solution containing sodium silicate.

Other objects will appear from the following description and appended claims.

According to one mode of practising the invention, cakes. of artificial silk after removal from the buckets are provided with resilient 0 foraminous aluminum inserts and disposed on washing racks where they are washed free of the coagulating bath liquors. After desulphuring and washing, they are subjected to the bleaching solution more specifically described 5 hereafter in any of the well-known manners, as by causing it to drip onto the cakes until the proper degree of bleaching has been effected. The cakes are then washed with water or treated with any common anti-chlor, precautions being 7 taken not to subject the yarn to any acid treatment until all of the sodium silicate has been removed. The yarn is then subjected to any finishing operation, such as lubrication, sizing, dyeing, tinting, and finally dried.

The state or condition of the artificial threads in no wise interferes with the successfulpractice of the process. I prefer, however, to bleach the cakes after the desulphuring and washing treatments without any preliminary drying and -while the threads are still wet and in the gel state. On the other hand, if desired, the cakes may be dried after the desulphuring and washing treatments and prior to the subjection to the bleaching operation.

The bleaching solution which I propose to use comprises a hypochlorite and an agent, such as sodium silicate, which inhibits the corrosive action of the hypochlorite on the aluminum. Va- I riousv proportions of the ingredients may be 90 used. It is desirable, however, that the amount of the sodium silicate should not be greatly in excess of that required toinhibit the corroding effect of the bleaching solution on the aluminum. A quantity greater than this renders the 5 system too alkaline and results in a-poor bleaching. Specifically, the amount of sodium silicate present in the bleaching solution should-not ex- .ceed approximately 0.5% Preferably, I use a cess ful results have been obtained by using the solution at room temperature. though also satisfactory, have been secured by employing the solution in a cooled or heated state.

Though the invention has been specifically described in connection with the drip method of bleaching cakes, it is not restricted thereto. is equally applicable to treating yarn contained on aluminum bobbins, to immersion treatment, to pressure or vacuum bleaching and even to a centrifugal operation in spinning buckets.

In addition to inhibiting the corrosion of the aluminum carriers by the bleaching compound, the bleaching solution hereinbefore described produces a yarn of increased whiteness and of somewhat greater tensile strength.

It is to be understood that the term aluminum used in this specification also embraces and includes aluminum alloys.

Since it is obvious that various changes may be made in the specific details above mentioned, this invention is not restricted thereto except as set forth in the appended claims.'

I claim:

.1. In a method of producing artificial threads from viscose the step of bleaching the threads disposed on aluminum carriers which comprises subjecting said threads and carriers to a hypochlorite bleaching solution containing a suflicient quantity of sodium silicate to inhibit the corrosion of the carriers by the hypochlorite.

2. In a method of producing artificial threads from viscose the step of bleaching the threadsdisposed on aluminum carriers which comprises subjecting said threads and carriers to a hypochloride bleaching solution containing sodium silicate, said solution having an available chlorine content or not more than 0.2% and a silica content of not more than 0.2%.

3. In a method of producing artificial threads from viscose the step of bleaching the threads disposed on aluminum carriers which comprises subjecting said threads and carriers to a solution containing an alkali hypochlorite and a sufficient quantity of sodium silicate to inhibit the corrosion of the carriers by the hypochlorite.

4. In a method of producing artificial threads 5 from viscose the step of bleaching the threads disposed on aluminum carriers which comprises subjecting said threads and carriers to a solution containing an alkali hypochlorite and sodium silicate, said solution having an available chlorine content of not more than 0.2% and a silica content of not more than 0.2%.

5. In a method of producing artificial threads from viscose the step of bleaching the threads disposed on aluminum carriers which comprises subjecting said threads and carriers to a solution containing an alkali hypochlorite and sodium silicate, said solution having 0.05% to 0.2% available chlorine, an alkalinity of 0.02% to 0.1% calculated as caustic soda and a silica content of 0.02% to 0.2%.

6. In a method of producing artificial threads from viscose the step of bleaching the threads disposed on aluminum carriers which comprises subjecting said threads and carriers to a hypochlorite bleaching solution containing a sufficient quantity of sodium silicate to inhibit corrosion of said carriers by the hypochlorite, said threads being in the gel state.

'7. In a method of producing artificial threads from viscose the step of bleaching the threads disposed on aluminum carriers which comprises subjecting said threads and carriers to a hypochlorite bleaching solution containing sodium silicate, said solution having an available chlorine content of not more than 0.2% and a silicia content of not more than 0.2%.

8. Ina method of producing artificial threads from viscose the step of bleaching the threads disposed on aluminum carriers which comprises subjecting said threads and carriers to a solution containing sodium hypochlorite and a sufficient quantity of sodium silicate to inhibit corrosion of the carriers by the hypochlorite, said threads being in the gel state.

9. In a method of producing artificial threads from viscose the step of bleaching the threads disposed on aluminum carriers which comprises subjecting said threads and carriers to a solution containing sodium hypochlorite and sodium silicate, said solution having 0.05% to 0.2% available chlorine, an alkalinity of 0.02% to 0.1% calculated as caustic soda and a silica. content of 0.02% to 0.2%, said threads being in the gel tate.

Variable results,

THOMAS P. BANIGAN.

CERTIFICATE OF CORRECTION.

Patent No. 1,931,245. October 17, 1933.

moms F. BANIGAN.

it I! hereby certified that error appears in the printedcpecificction of the above numbered patent requiring correction as follows: Page 1. line 28, for "succesfully" read successfully; page 2, line 37, claim 2, for "chloride" reed chlorite; and line 105, claim 7, after "0.2%" incert the words nid threads being in the gel state; and that the uidLetterc Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of November. A. 11.1933.

I M. Hopkins (Seal) Acting Comieeioner of Patents. 

